Alliedsignal Inc.

Avco Corporation

Howmet Corporation

Prabir Ranjan Bhowal

Howard F Merrick

Donald E Larsen, Jr

William A Konkel

Process for improving the mechanical properties and ultrasonic inspection efficiency of alpha-2 titanium aluminide forged products, parts or components and for preserving or retaining these improved properties at use temperatures up to about 1200.degree. F. The process involves heating a billet of the alloy below its beta transus temperature, forging the heated billet within a true strain range of about 1.2 and 1.4 and within a strain rate of about 0.1 and 0.15 per second to produce &gt;90% refinement of prior .beta. grains to a typical size less than about 0.2 mm, preferably about 0.02 mm, and cooling the forged billet to room temperature. A heat-treatment may be applied by rapidly cooling to room temperature to form the transformed beta phase with no precipitation of alpha platelets, and then heating to a transformation temperature (T) for a period of time (t) to form a beneficial orthorhombic crystalline phase microstructure including very fine alpha-2 particles, and not heating the alloy again above the use temperature of 1200.degree. F., whereby the beneficial microstructure is retained and remains stable for extended periods of exposure at or below 1200.degree. F.

Process for producing forged .alpha.-2 based titanium aluminides having

Creep resistant titanium aluminide alloy article consisting essentially of, in atomic %, about 45 to about 48 Al, about 1.0 to about 3.0 Nb, about 0.5 to about 1.5 Mn, about 0.25 to about 0.75 Mo, about 0.25 to about 0.75 W, about 0.15 to about 0.3 Si and the balance titanium. The article has a heat treated microstructure including gamma phase, alpha-two phase and at least one additional particulate phase including, one or more or W, Mo, and Si dispersed as distinct regions in the microstructure.

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Huntington, CT, United States of America

Prabir Ranjan Bhowal